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Bridge retrofitting of a section of the Berlin subway which is designed as railway on steel viaduct is presented. Fatigue damage in the superstructure of the over 70-years-old viaduct made an investigation of the damage causes necessary prior to the planning of retrofitting measures. The damage specifically occurred at the inverted arched steel plates of the ballast support elements. Those plates were provided for carrying the track ballast as well as the traffic load. For the retrofitting, the inverted arched plates were unloaded. The superstructure was redesigned into a fixed track system, which is able to transfer the traffic load directly into the substructure. The new rail fastening system made it necessary to verify the structural integrity of single elements as well as of the main system of the existing viaduct. The verification was based on several experimental investigations at BAM laboratory and on-site. Based on the evaluation of all test results the operation license could be issued.
Impact limiting components of packages for the transport of radioactivematerials are often designed as wood filled steel constructions. Wood absorbs major part of the impact energy in order to minimise the impact load acting upon the containment. Dynamic impact experiments with wood filled impact limiters showed different crushing mechanisms for axially loaded wood depending on their lateral constraint. Tests on spruce wood samples (Picea abies) were performed in order to clarify the influence of strain rate from static to 30 s-1 on a) compression strength, b) stress at a global strain level of 50%, and c) energy absorption capacity at 50% deformation, including statistical evaluation of the results. Results were as follows: strain rate increase led to significantly higher compression strength, stress and strain energy at a strain level of 50%. Lateral strain restriction had no effect on compression strength; it had a significant effect on stress and strain energy at strain level of 50%. Therefore, the definition of a general yield curve for wood under large deformations is not possible, the yield curve has to be chosen taking into account lateral constraints.